1. Field of the Invention
The present invention relates to a heater. In more detail, the present invention relates to a heater usable for heating a lubricating fluid such as engine oil and a transmission fluid.
2. Description of Related Art
There are machines operating with parts grinding against each other. For example, in an internal combustion engine such as an engine, many parts grind against each other during a process where a piston moves up and down in a cylinder. When parts grind against each other in such a manner, abrasion or heat generation may be caused in the parts, and it may cause a defect in the machine.
Therefore, there is used a lubricating fluid in order to suppress abrasion and heat generation by reducing friction when parts grind against each other. For example, in order to suppress abrasion of parts and heat generation in an engine, engine oil is used as a lubricating fluid. Thus, in order to operate a machine which operates with parts grinding each other, a lubricating fluid is indispensable. However, in the case that such a lubricating fluid is at low temperature, the lubricating fluid has high viscosity. As a result, there arises a problem of impossible sufficient reduction of the friction. In addition, when the viscosity of the lubricating fluid becomes high, there arises a problem of impossible supply to an intended position.
In order to cope with the problems, the lubricating fluid is heated by a heater. This enables to appropriately lower the viscosity of the lubricating fluid and to reduce the friction well by the lubricating fluid. However, when the lubricating fluid is excessively heated, a disadvantage of causing deterioration of the lubricating fluid is occurred. Therefore, there have been proposed various heaters having a mechanism of not heating the lubricating fluid excessively and the like (e.g., Patent Documents 1 to 3).